@brianruss,
You can google the volume of a 40ft HC container in cu metres
Divide that volume by the volume of a box (lengthxbreadthxheight) using the same units for each.
(NB cu cm = cu metres x 1,000,000 and your box appears to be in mm so divide by each length 10 to get cm)
Your answer will be approximate since the shape of the box may exclude filling the total volume